National Repository of Grey Literature 18 records found  1 - 10next  jump to record: Search took 0.00 seconds. 
Modeling migration of pharmaceuticals
Osipenko, Ivan ; Závodská, Petra (referee) ; Klučáková, Martina (advisor)
The presented bachelor thesis deals with the problem of the possibility of sulfapyridine diffusion in soil systems. The main objective of this thesis is to propose a simple mathematical model to calculate and explain the possibility of drug migration in soil systems using the example of diffusion in agar gel in the presence of humic substances as the main component of organic matter in soil. In the present bachelor thesis, simulations of sulfapyridine diffusion in porous media, influenced by chemical side reactions of different series, were carried out. For these calculations COMSOL Multiphysics software and the corresponding packages "Chemistry" and "Transport of diluted species in porous media" were used, allowing simulations of real processes. The modelling results showed that the addition of reactive components to the hydrogel have an effect on the migration of sulfapyridine due to the interactions taking place during the diffusion. Reactions of different orders, including back reactions, were added successively to the simulations in inert media. The results obtained showed that the probable sum interaction mechanism has less influence on migration than the interaction of other mechanisms.
Thermal Mass Flowmeter
Mlčoch, Albert ; Kunz, Jan (referee) ; Beneš, Petr (advisor)
The thesis deals with the design of a mathematical model and practical implementation of a flowmeter based on the thermal principle. The range of the proposed flowmeter is from units of kilograms per hour to lower hundreds of kilograms per hour. The design of the flowmeter is non-invasive to the flow channel, the heating element is located outside the pipe. In this paper, the flowmeter parameters are identified and a temperature regulator is proposed. Measurements are made on a test bench. The results of the measurements are discussed. Modifications to the existing hardware are suggested.
Reduction of temperature inhomogeneity in power modules
Soboňa, Matúš ; Maxa, Jiří (referee) ; Vyroubal, Petr (advisor)
This master thesis shows multiple methods for the reduction of temperature inhomogeneities in power modules. A heat transfer simulation on model power module is performed based on the settings of real world thermographic measurement, results are compared. The shown methods are analyzed and their real world applications are discussed.
Influence Of Piezoelectric Material Properties On Impedance Characteristic And Improvements Of Calibration Equipment
Krejčí, Jakub
This paper deals with finite element simulations of impedance characteristics piezoelecticelements utilized in sensors of acoustic emission (AE). Coefficients of piezoelectric material arechanged to evaluate the sensitivity to their variation in case they are not known precisely, so to whichextent can they influence the sensitivity of the sensor. Result showed sensitivity on coefficient inc-matrix, mainly to coefficients c11 and c13. Second investigated topic is issue with test stand for calibrationof AE sensors, where output of force sensor was affected by parasite signal. By contactlessmeasurement with laser interferometer was discovered the parasite signal is caused by mechanic ofthe system and it is no threat for the measuring chain.
Simulations And Measurement Of Acoustic Emission Effects
Krejčí, Jakub
This paper deals with issue of method of acoustic emission and performed measurements of acoustic emission signals and simulation of this phenomenon. Main interest is given into measurement of acoustic emission transducer displacement to verify homogeneity on its surface in time and simulations by finite element method. Performed simulations deal with displacement calculation of calibration block after a capillary break, calculation of impedance characteristics of piezoelectric sensing element and their comparison with analytic solution or measurement.
Modelling of particle thermal motion
Orság, Miroslav ; Sedláček, Petr (referee) ; Pekař, Miloslav (advisor)
The goal of this thesis was to get familiar with the basics of mathematical description of the thermal motion of particles in a given media, and with other possibilities of the software package COMSOL Multiphysics. A model for viscous and viscoelastic environments was created, a uniform and user friendly system for simulation and calculation of MSD and system for data conversion from FCS to MSD. Furthermore, the possibilities of the model for use in microrheology were assessed and another procedure in the implementation of the COMSOL program in the characterization of gels was proposed.
Simulation of point contact lubrication by finite element method
Hrdonka, Štěpán ; Čermák, Jan (referee) ; Šperka, Petr (advisor)
This diploma thesis is concerned with simulation of elastohydrodynamic lubrication of point contacts using the finite element method. The first part of the thesis focuses on the study of the issue and introduces equations for model creation and numerical methods which can be used for EHD calculation. The most suitable solution approach has been chosen from the overview, namely the Full system approach. The software we chose for applying the method was COMSOL Multyphysics. The following part of the thesis deals with model’s creation and gives its elaborate description. We introduce models for calculation of line and point EHD lubrication for newtonian lubricants and, last but not least, we also present a model for calculation of point contact EHD lubrication for non-newtonian lubricants. The next part of the thesis then verifies all the models. That is achieved by comparing the calculated results to results from different papers. The conclusive part of the thesis then examines the matches of acquired results to different prediction relationships and experiments.
Simulation of heat transfer in the program COMSOL Multiphysics
DOLEŽAL, David
This bachelor thesis deals with the study of heat conduction in solids and the creation of a model in the commercial program COMSOL Multiphysics. The work is divided into five thematic units. The first part deals briefly with the meaning and characteristics of both the program and the heat transfer module. Heat, as one form of energy, accompanies all the physical processes we can encounter and is an integral part of our lives. In this connection, the basic physical mechanisms of heat transfer, such as conduction, flow and radiation, are presented in the second part. Attention is also paid to physical variables, theories and concepts whose knowledge is necessary to investigate heat transfer mechanisms. The third part of the thesis is devoted to the experiment, consisting in the observation of temperatures of heated materials by a thermal camera. In the fourth part of the thesis are first described in general the steps accompanying the production of the model and subsequently production of a particular model in the program itself. The last part of the thesis is devoted to comparing experimental results with data from the model.
The effect of electromagnetic fields on cell structure
Urbánek, Jiří ; Fiala, Pavel (referee) ; Vlachová Hutová, Eliška (advisor)
The main concern of the work is researching the influence of electromagnetic field on cellular structures. Cellular structures is a general term for all the organelles placed in a cell. In our 2D model we take into consideration just the fundamental organelles such as cell membrane, cytoplasm and cell nucleus. The aim of the work was to get acquainted with the outer environment into which we had placed the 2D model of the cell and on which we had applied the magnetic field. The work contains the results gained by numeric modelling in the physical programme COMSOL. These results prove the theoretical presumption.
Change of magnetic susceptibility during the germination of plants
Sedlář, Petr ; Fiala, Pavel (referee) ; Vlachová Hutová, Eliška (advisor)
The work examines the changes in the magnetic susceptibility during the early germination of the somatic embryo (RSE) of the Norway spruce. Susceptibility is in the physically view the property, which can be used to determine a variety of parameters and properties of the measured objects. The aim of this work was to create a automatic to evaluate the susceptibility of the tissue RSE and take measurements to prove or disprove the contrary of the accuracy of this assessment. This work contains the results obtained by modeling a script in Matlab, in which can be shown the correctness of the theoretical concepts.

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